From Naked SuperFood Green Machine "food-juice" to Red Bull, a growing number of specialty beverages are offering to quench more than consumers' thirst.

Often billed as health drinks, these new products contain a wide range of ingredients, from the Brazilian berry acai (pronounced AH-sigh-EE) to taurine, an amino acid that occurs naturally in meat. Some of these drinks promise to boost energy, promote immunity or bridge the nutritional gap for those not eating up to par. Others are aimed at people who simply seek a healthier alternative to low-nutrition soft drinks.

Even makers of beer and malt beverages are getting into the act. In January, Anheuser-Busch introduced B{+E} , a beer infused with caffeine, ginseng and guarana, a jungle vine that produces caffeine-rich yellow fruit. Drinkers of Sparks malt liquor get caffeine and taurine in their brew.

How much of these added ingredients the drinks deliver varies widely. In many cases, "the amount is usually going to be pretty negligible," notes Leslie Bonci, director of sports nutrition at the University of Pittsburgh Medical Center. "Otherwise you'd be paying a ton, and it probably wouldn't taste that good."

Even so, the drinks can take a bite out of your wallet, often running about two dollars per can or bottle.

"Calorie-wise, you're not saving anything with these drinks," said Bonci, who is a nutritional consultant to the Pittsburgh Steelers football team. "You could eat a big salad for a lot fewer calories and won't be as hungry as a result."

As for sipping a diet Red Bull or diet Rock Star energy drink before a workout, Bonci said a healthy snack -- a bowl of vegetable soup, for example -- is a better idea. "I tell my athletes, 'If you want to have energy for a workout, you need calories,' " she said.

Here's a rundown of some of the ingredients now included in specialty drinks:

Acai Purveyors of drinks that use these palm berries claim they contain high levels of antioxidants and other ingredients that could have wide-ranging health benefits. The National Institutes of Health's Office of Dietary Supplements lists only two studies on acai. One examined its use as a contrast agent during magnetic resonance imaging (MRI); the other looked at its chemical composition and pigment stability.

Ginkgo biloba. Commission E, a group convened by Germany's Federal Institute for Drugs and Medical Devices to examine safety and efficacy of herbs and plant-based medicines, has approved gingko to treat a type of dementia. Some studies hint at possible heart benefits for gingko, which appears to have some estrogen-like activity. No answers are definitive yet. The Food and Drug Administration does not include ginkgo in the generally regarded as safe (GRAS) category of foods, nor has it approved its use as a drug. Products with ginkgo can be sold as dietary supplements provided they make no claims about their ability to prevent, diagnose, treat or cure disease.

Ginseng. Both Commission E and the World Health Organization say this root herb native to China, Korea and eastern parts of Russia can help combat fatigue and improve concentration. Those with hypertension and other cardiovascular problems are advised not to use it by the Physicians' Desk Reference for Herbal Medicines. The Office of Dietary Supplements provides no fact sheet on ginseng.

Green tea. This popular beverage can help boost metabolism a little. Green tea is rich in antioxidants. Numerous studies are underway to see if it could protect against cancer or treat it. Nothing definitive yet.

Guarana. Rich in caffeine, guarana is a powerful stimulant. Whether it remedies fatigue is unproven, according to the Physicians' Desk Reference for Herbal Medicines, which lists one gram as the daily dosage -- about the amount found in 2 1/2 of Rock Star's 16.5-ounce cans. One study in rats found that guarana protected the stomach against alcohol damage. Whether it does so in humans isn't known.

Milk thistle. Commission E approves extracts of this plant for dyspepsia, liver and gallbladder complaints. A review by the U.S. Agency for Healthcare Quality and Research found that milk thistle may help repair liver disease and cirrhosis, although it cautioned that many of the studies lacked scientific rigor. Health drinks with milk thistle contain only about 20 milligrams per serving -- about a tenth of what Commission E recommends for therapeutic doses. Side effects may include nausea, diarrhea, flatulence, headache and abdominal fullness or pain.

Omega-3 fatty acids . Rigorous scientific research shows that these healthy fats are good for your heart and likely good for your brain, your joints and possibly even your mood. A 15-ounce bottle of Odwalla's Berries GoMega delivers 1,300 milligrams of alpha-linolenic acid, enough to slightly exceed the daily adequate intake (AI) set by the National Academy of Sciences for women and nearly meet the AI for men. But that's just one type of omega-3. Two servings of seafood per week provides the AI for both types.

Spirulina . This edible algae is rich in protein as well as vitamins A, D, K and B12. Some studies hint at cancer protection. But skip it if you have any autoimmune disorders. A recent report in the Archives of Dermatology linked spirulina to development and flare-ups of a rare autoimmune disease -- pemphigus vulgaris -- that produces painful body sores.

Taurine. Studies of taurine supplementation are mostly limited to animals. A few human studies point to some potential for use of taurine in congestive heart failure. One study in humans found that taurine when taken with vitamin C may help protect blood vessels in young smokers. But other human evidence is lacking. "There's really nothing here from a human perspective," Bonci said. ·